The newest installment:
We saw a marriage counselor today. She suggested separation, which he seems to have jumped on. Insisted that his "friend" was just that, said that they only shared "one kiss." (It was a make-out session that she photographed, and sent pictures to my home.) I noticed that he was texting her before the session ended. He explained that he wanted to "see what happens to the marriage" before "pursuing her" (remember, just friends, and he says that he is not attracted to her.") Counselor suggested that it actually works in the opposite order: stop the "friendship" and then see where the marriage goes.

Took our separate cars home. He immediately wanted to talk about separation, and I said "let see if we can stop arguing first." Take a few days to think about it. He is supposed to start therapy today, but I doubt that he will go. He is still lying about the OW, and is also upset that his niece just sent a friend request to instagram, no doubt to "spy on her to get dirt."

What to do?